Please advise correct solution for Search help

Hi ,

i want to develop a webdynpro application( in ECC 6) which takes data from 4.6C . So i have to provide my own search helps to certain fields ( like material number) .

As i am very new to webdynpro i planed to make search helps in ECC and using search help exit and RFC ( fetching data from 4.6c) fill data to these search helps and assign this to webdynpro fields. Is it make a -ve effect on perfomance? is there any alternative way to do this ? please advise.